Controlling mechanism



Aug. 21

F. D. HOLDSWORTH CONTROLLI NG MECHANI SM Filed July 6, 1920 Egg. 1. 6 V7 Patented Ang.21, 1923.

mean? FRED n. HoLnswon'rn; or CLAREMUNT, new HAMPSHIRE, ASSIGNOR T SULLIVAN MACHINERY COMPANY, a CORPORATION or MASSACHUSETTS.

CONTRDLLING MECHANISM.

Application filed July 6,

T 0 all whom it may concern.-

- Be it known that I, FRED D. HoLDswoR'rH, a citizen of the United States, residing at Claremont, in the county of Sullivan and State of New Hampshire, have invented cer tain'new and useful Improvements in Controlling Mechanisms, of which the tollowing is a full clear and exact specification.

My invention relates to controlling mechanisms and moreparticularly to compressor controlling mechanisms.

An object of my invention is to provide an improved compressor controlling means. Another object or my'invention is to provide an improved controlling mechanism for motor driven compressors of the type wherein the motor is stopped and started and the compressor loaded and unloaded in accord ancc with variations in compressor discharge or receiver pressure. Further objects of my invention. will appear in discourse of the tollowing specification and claims.

In the accompanying drawings I have shown for purposes of illustration, one form which my invention may assume in practice.

In these drawings,

Fig. 1 is a side elevation of a compressor system provided. with my improved controlling mechanism, a portion of the compressor cylinder being broken away to show the inlet valve mechanisms. 1

Fig. 2 is a central vertical section through the control mechanism which I have usedas an illustrative embodiment of my invention.

Fig. 3 is a detail on an enlarged scale on the same line as Fig. 2. i

Fig. 4; is an enlarged sectional View of the switch mechanism.

I have shown my improved compressor controlling); mechanism in'combination with a compressor system comprising a compressor 1 having a cylinder 2. discharge mechanism generally indicated by 3, and inlet mechanism generally indicated by 4 and which will be more tully described later. The compressor 1 is driven by a motor 5 which is supplied with current through mains-6 and 7 under control of a switch 8 which is of the magnetic control type, being controlled by themagnet 9 and the latter is controlled by mechanism which will be. described hereafter. The compressor inlet mechanism consists of a plurality of inlet valves 10 01 which but one is shown, these valves being provided. with stems 11 and 1920. Serial No. 394,297.

being normally held closed by a spring 12 which is of such strength as to be overcome by the suction produced by the movement of the piston on the suction stroke. For the purpose ofunloading the compressor, plungers 13 are provided in cylinders 14. These plungers, when subjected to fluid pressure on their lower sides, tend to raise the stems 11 and accordingly maintain them open whereby the air is permitted to pump into and out of the cylinder as the piston reciprocates. Fluid pressure is supplied to and conducted away from the cylinders l by piping 15 which is under the control of my improved i'nechanism the details of which will now be described.

For the purpose of controlling both the operation of the motor 5 and the position of the inlet valves, I have provided controlling mechanism whose illustrative embodiment is most clearly illustrated in Fig. 2. This mechanism comprises a cylinder 16 in which a piston 17 is reciprocable, the piston being subjected to the action of a spring 18 which normally holds it at the top of its cylinder 16 and being adapted to be moved clownward by fluid pressure transmitted to the top of the chamber 16 by way of a port 19. At this point attention is directed to'the fact that large clearance volume is provided as indicated at 20 at the top of the chamber 16. the purpose of this clearance volume being to provide a considerable quantity of air in the cylinder, which air will take a considerable time to exhaust, as later descri'bed.- The port 19 is controlled by a check valve 21 and the check valve 21 is provided with a central vent of small size as indicated at 21. Fluid pressure is supplied to the check valve which opens toward the cylinder 16 by way of the connection 22 and the latter is controlled by means of a well known type of pilot valve, here shown as the Judson type. This pilot valve, which is designated 23. has a connection 24 with the receiver 25 which receives the discharge from the compressor cylinder 2 and is also provided with a small exhaust port 26. The operation of the pilot valve. as is wellknown, is such that upon rise of receiver pressure above a desired limit,- the pilot valve will open and transmit the pressure through the connection 22 while closing the exhaust 26. When. however. the pressure falls below a ce tain slightly lower desired limit, the pilot 'valvewill close the communication between the connections 24 and 22 and will place the connection 2:2 in communication with the exhaust 26, thereby placing the cylinder 16 in communication with the atmosphere. will thus be seen that the piston 17 will be caused to move downwardly at such time as fluid pressure in the receiver exceeds a pre determined desired amount, and will move backward at a retarded rate due to the ne cessity of fluid pressure escaping from above it by way of the vent 21 in the check valve 21 upon the falling of the pressure within the receiver below a predetermined desired limit. The piston 17 is provided with a projecting rod 27 which carries at its lower end a cross head 28 and the latter moves in a cylindrical guide chamber 29 secured to the lower end of the cylinder member 16. At the bottom end of the cross head member is an adjustable contact element 30 which is in .turn adapted to impinge upon a pin 31 which controls a switch 32 of a "well known type, the switch 32 being so arranged at the lower end of the guide member 29 as to have its control pin 31 impinged by the contact member 30 when the piston 17 reaches the bottom end of its stroke. The switch 32 is so constructed that when the member 31 is "forced. downwardly the circuit which controls the magnet 9. is opened. thereby causing the opening of the main circuit through the motor 5 and upon release of the plunger 31 by upward movement of'the piston, the circuit 33 through the magnet 9 is at once closed in such a manner that the motor resumes operations.

From the foregoing description of the operation of the piston 17, it will be obvious that the motor. will be promptly stopped and promptly started in accordance with variations in pressure in the receiver.

For the purpose (it controlling the inlet valves I have arranged a alve 34 controllingthe connnunication 01 a connection 24L with the piping 15m The valve 34 ispro vided with a surface 35 adapted to cooperate with a stationary'seating surface Miami is provided with radially extending holes'37 opening into the interior of the valve. The valve is also provided with a'surtace 3S opposite thesurface 35 which is'adapted, when the'va'lve is in its opposite position, to seat upon a stationary annular seating surface 39 and the valve is adapted to be moved in opposite directions by fluid pressure and by a plunger 40 which is slidably mounted in an opening in the valve casing 41.. The plunger 40 is surrounded by an annular exhaust port, extending up to the seating surface 39. and this exhaust. port, indicated here as 4:2. communicateswith the atmosphere as indicated at 43. It will be obvious that as the plunger 40'is pressed to the right the surface 35 will seat upon the seat 36 and close communica tion between connections 24' and 15, while opening a communication between connection 15 and the atmosphere by way-of openings 37, e2, and43, and'tha-t in the reverse position of the valve, a communication between pipes 35 and. 15 willbe opened, while 15 with the exhaust For the purpose of controlling the operation of the plunger 4L0 I have arranged a cylindrical transverse opening 44 through the cross head member 28 and mounted herein two balls which are ota greater combined diameter than the .diameterof the cross head member 28. For the purpose of actuating the plunger 101 have arranged a spring et6 which is mounted in a shallow notch 47 extending longitudinally of the member 29. This spring 46 constitutes in effect a lever, beingfixed at its lower end and having its upper end engaging the plunger 40 so that when pressure is applied adjacent the upper end of the mem ber 5L6, the plunger 40 is moved bodily. As will be noted, when the cross head 28 is at the bottom of its travel, the spring or lever is relieved of the pressure exerted upon it by the balls 45 and pressure through the connection 24; will open the valve '34 and supply fluid to the plungers 14,'the connection to the exhaust being closed at this time. Vhen the cross head 28, however,1 reaches the position shown in Fig. 2, i. e., the opposite end of its stroke, the balls 45 force the 3 spring at against the plunger and close the connection between pipesQet and 15 and place pipe 15 in communication with the exhaust It will-be observed that owing to the resilience of: the lever or spring 46,the movement of the valve will be very sharp and it will snap from its left hand position to its right hand posit-ion assoon as a sutficient pressure is exerted upon the member 46 by the balls to cause the pressure to move the valve off of its seat upon the surface 39.

The operation of the device is as follows: hen the pressure in the receiver 25 exceeds a predetermined amount, the pilot valve 23 will operate 'tosupply pressure through connection 22 and check valve 21 to the cylinder 16 and force downward the plston 17' thereln. The piston 17 in its downward movement causes thecross head 28 to move downwardly and progressively j cordingly open and. fluid pressure fromthe receiver will be transmitted by way of pas sage 24-and passage 15 to the plungers 13 and cause the opening of the inlet valves 10 and maintain them in an open position. The

contact member 30 will valso impinge upon g the plunger 31 and soopen the circuit controlling the magnet 9, and so othe main.

mot-orstopped. As a result, the compressor 7 plant will be completely shut down. 7 hen the pressure in the receiver falls to a desired degree, the pilot valve 23 will be operated to close communication between the line 2% and the connection 22 and will open the exhaust port 26. The piston 17 will accordingly bemoved upward :hy the spring 18 as rapidly as the air within the upper end of the cylinder and the chamber 20 can be expelled through the'vent 21 in the check valve 21. The upward'movemcnt oi: the piston will first free the switch controlling pin 31 and thereby cause the starting of the compressor motor, due to the fact that the magnet circuit having been closed, the main circuit will likewise be closed, When, after the interval occasioned by the delay in the upward movement of the piston 17, the cross head 28 moves up suiiiciently far to place the spring l6 under such pressure as to oven come the air pressure acting upon the surface 85, the valve 34 will. interrupt communication between connections 24; and 15 and will. simultaneously open communication by way of ports 3'7, 42 and 43 between the pipe 15 and the atmosphere. thereby permitting the plungers 13 'to fall and the inlet valves to close. As a result, the compressor will be loaded, but, due to the delay during the escape ofthe fluid from the topof the cylinder 16 and from the chamber 20 through the restricted vent 21' in the check valve 21, the motor will have brought the compressor to full speed prior to the time when a load is thrown upon it. It will be noted that when the valve 34 is first moved by the plunger 40 from its left hand seated position, additional area will become exposed to pressure and so the spring 46 will effect a sharp throw of the valve.

While I have in this application specifically described one form which my invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that the invention may be modified and embodied in other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a compressor controlling mechanism. in combination, compressor unloading means and a controlling valve therefor. a lever contacting therewith adjacent one end thereof and having a fixed fulcrum. and force applying means moving relatively longitudinally of said lever in consequence of compressor discharge pressure variations.

2. In a compressor controlling mechanism, in combination, compressor unloading means and a controlling valve therefor, a lever contacting therewith adjacent one end thereof and having a. fixed fulcrum, and force applying means movingrelati-vely longitudinally of said lever to decrease the dist-ancev betweenthe point of application of the-force and the point of contact with the control valve in consequence of compressor discharge pressure variations.

3. In a compressor controlling mecha nism, in combination, compressor unloading means including a control valve and a flex- 'ible lever. for actuating the same, and means movable in response .to compressor discharge pressure variations in a direction generally longitudinally of said lever, to vary the flexure of said leve adjacent its point of contact with the control valve.

l. In a compressor controlling mechanism, in combination, a compressor unloading mechanism, a control valve therefor, and

means for moving said valve sharply including a flexible lever for actuating said valve and means movable in consequence of compressor discharge pressure variations operative to flex said lever to cause the latter to impose upon said valve an increasing press- 1 sure.

5. In a compressor controlling mechanism, in combination, a fluid pressure operated unloading mechanism, a control valve therefor operative-in opposite positions to cause sup' ply of fluid to said mechanism to unload the compressor and to connect said mechanism with exhaust to cause loading of the compressor, said valve being biased to the first named position by fluid pressure, and means including a flexible lever and means for flexing the same to cause said valve to move sharply from first to second position.

6. In a compressor controlling mechanism,

in combination, a fluid pressure operated compressor unloading mechanism, a control valve therefor, and means for moving said valve sharply including a flexible lever for actuating the valve, said lever being movable in consequence of compressor discharge pressure variations and operative when positively moved to shift said valve to interrupt supply of fluid to said pressure unloading mechanism and open a vent therefrom.

. 7. In a compressor controllingmechanism, in combination, a compressor unloading means, a controlling valve therefor, a resilient lever for actuating the latter, and means movable in consequence of compressor discharge pressure variations to cause said lever to release said valve to permit the movement thereof in one direction and to move said valve sharply in the opposite direction and elastically retain it in its opposite position. 7

8. In acompressor controlling mechanism, in combination, a compressor unloading means, a controlling valve therefor cooperating with opposed seats, a flexible lever for actuating the valve to move the same sharply from one seat to another, and means movable in consequence of compressor d1s-.

chargepressure variations to move said lever and having a greater range of movement than the portion of said lever with which it cooperates. 7

contact device on said second mentioned member adapted to actuate said first mentioned controlling means, a flexible member engageable with said second mentioned controlling means, and means carried by said second mentioned member having rolling contact with said last mentioned member, and operative to force the same into yielding contact with said second mentioned controlling means. 7 e

10. In a compressor controlling system, in combination, a compressor, a driving motor therefor and a receiver, driving motor starting and stopping means, control means therefor, compressor unloading means, con trolling means therefor, a member reciprocable in consequence of receiver pressure variations, a member movable therewith, a contact device on said second mentioned member adapted to actuate said first mentioned conmeans, and a ball rotatably mounted in said second mentioned member having rolling contact with said last mentioned member and operative to force the same into yielding contact with said second mentioned controlling means. I V

11. In a compressor controlling mechanism, in combination, compressor unloading means and a controlling valve therefor, a lever contacting therewith adjacent one end thereof and having a fixed fulcrum, a guide making a smallangle with said lever, and force applying means moving relatively longitudinally of and between said lever and guide in a direction toward the vertex of said angle in consequence of compressor discharge pressure variations.

12. In a compressor controlling mechanism, in combination, compressor unloading means and a controlling valve therefor, a lever contacting therewith adjacent one end thereof and having a fixed fulcrum, and force applying means having a rotatable member which engages said lever and is adapted to roll therealong, and moving relatively longitudinally thereof to decrease the distance between the point of application of the force and the point of contact with the, control valve in consequence of compressor discharge pressure variations.

In testimony whereof I aflix my signature.

FRED D. HOLDSWOR-TH. 

